Guided wave testing is widely used to inspect and monitor many types of structures. The method uses mechanical waves that propagate along a structure while guided by its boundaries. This allows the waves to travel a long distance with little loss in energy.
One type of guided wave testing is magnetostrictive sensor (MsS) testing, developed at Southwest Research Institute®. MsS testing was originally developed for guided wave wire rope and cable inspections, and earlier patents describing it are U.S. Pat. Nos. 5,456,113 and 5,457,994. A known MsS method generates (and detects) longitudinal guided waves directly in the cable. A known MsS probe for the method comprises an MsS wire coil and a DC biasing magnetic circuit. The MsS wire coil encircles the cable, and the DC biasing magnetic circuit is placed directly on the cable.
Various types of MsS probes may be used to implement MsS testing of wire ropes and cables. An MsS probe that is light-weight, relatively inexpensive, and operates independently of the cable material is described in U.S. Pat. No. 8,098,065.
MsS probes may be used to test structures other than cables, and the structure under test need not be cylindrical. Some MsS probes are designed for certain surface geometries, and some are adaptable for testing different surface geometries.
Various known MsS probes and MsS testing techniques, are described in the following patents, each incorporated herein by reference: U.S. Pat. No. 6,396,262 to Light, et al.; U.S. Pat. No. 6,917,196 to Kwun, et al.; U.S. Pat. No. 7,573,261 to Vinogradov; and U.S. Pat. No. 7,821,258 to Vinogradov.